And are there any other Atmel offerings which might be compatible? Would a SAM4S for example, which also comes in a 64 pin package, work with some tweaks? Or are the different arm processor types wholly incompatible with one another?
It would take a long time to get up and running on a different platform,
there probably isn't as large a community there to help out.
Palliser:USB host behavior? What functionality does that give you? Is that where it can act as a keyboard or mouse, or is it where it functions as removable storage media? Or does it allow it to interface with mice and removable storage media directly?
I've weened myself off the Arduino IDE completely